Error using "if" in R: "== : missing value where TRUE/FALSE needed" for spTransform

Question

I am trying to make the projection of a set of coordinates identical to a shape from wrld_simpl. But I keep getting the error below. How to solve that?

d=read.csv()
it= wrld_simpl[wrld_simpl$NAME == "Italy", ] 
d=na.omit(d)
d1=d[,c("lon","lat")]
coordinates(d1)=~lon+lat
d1=spTransform(d1,CRSobj="+proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 
+no_defs") 

Error in if (is.projected(obj)) { : valor ausente donde TRUE/FALSE es necesario Además: Warning message: In spTransform(xSP, CRSobj, ...) : NULL source CRS comment, falling back to PROJ string

• Agus camacho: here is the link to the file for a reproducible example: dropbox.com/scl/fi/wm0wok1f12ucjy3gw7ep2/…

Answer 1

There's a few problems here: d1 at the error point has an NA (missing) CRS so any attempt to reproject it with spTransform will fail.

On my system it fails with a different error message:

> d1=spTransform(d1,CRSobj="+proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs") 
Error in st_transform.sfc(st_geometry(x), crs, ...) : 
 cannot transform sfc object with missing crs

which makes me think you have an old version of sp.

To assign a CRS to an sp object you can use proj4string(d1) <- like:

proj4string(d1) <- "+proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs"

this is telling sp what coordinate system the numbers are. Since they look like lat-long WGS84 coordinates, I've used the proj4string you've got from the world map. At this point you should be able to plot them both with no more transformation needed:

> plot(it)
> plot(d1, add=TRUE)

enter image description here

If I plot the whole of the points and add the world it looks like everything lines up:

> plot(d1)
> plot(wrld_simpl, add=TRUE)

enter image description here

The other problem is that the sp package is deprecated and you should look at using the sf package and its data structures instead.

• Agus camacho: Thank you @spacedman! It seems I will have to stop delaying that shift to sf in my scripts.